鄂尔多斯盆地西缘桌子山地区上奥陶统拉什仲组深水复合流沉积
Deep-water Combined-flow Deposits of the Upper Ordovician Lashenzhong Formation in Zhuozishan Area, Western Margin of Ordos Basin
(a) 鲍玛序列Tc段黏土质粉砂岩中的叠置透镜体（长箭头）和复合流纹层，前者具有浪成波纹层理的不均一结构，后者具有明显的上凸纹层；(b) 准平行层理、正粒序层和复合流层理，复合流层理具有不对称的波峰（长箭头），纹层厚度向波谷变厚（短箭头）； (c) 准平行层理，上、下可见模糊的正粒序层；(d) 准平行层理、双向交错层理（水平箭头）和内部曲线型纹层（长箭头）的不对称小型似丘状交错层理；(e) 波状层理向准平行层理的转化，其上为不对称小型似丘状交错层理，内部为高角度曲线型纹层（箭头）；(f) 不对称小型似丘状交错层理，内部为低角度曲线型纹层（长箭头），丘状纹层向上渐变为水平纹层（短箭头）；(g) 对称小型似丘状交错层理，由向上变平缓的丘状纹层组成（箭头）；(h)同(g)，其下为爬升层理，含有上凸型纹层（长箭头）；b： 双向交错层理；c： 复合流层理；g： 正粒序层；h： 小型似丘状交错层理；q： 准平行层理；w： 浪成波纹层理，含不均一结构、束状体、波状层理等；(b)和（g）为中层细砂岩；(c)、(e)和(h)为薄层粉砂岩；(d)和(f)分别为薄层中砂岩和中层黏土质粉砂岩
(a) Amalgamated clayish siltstone lenses with discordant foresets (long arrow) and overlay combined-flow-ripple lamination with convex-up laminae in Tc division of Bouma sequence; (b) Quasi-planar lamination, normal graded layer and combined- flow-ripple lamination, note the asymmetric wave crest (long arrow) and thickening laminae toward wave trough (short arrow); (c) Quasi-planar lamination enveloped by amphibolous normal graded layer; (d) Quasi-planar lamination, bi-directional cross-lamination (horizontal arrow) and asymmetrical small-scale Hummocky Cross-Stratification-like structures (HCS-like) with curved internal laminae (long arrow); (e) Undulatory lamination changed laterally into quasi-planar lamination and overlay asymmetrical small-scale HCS-like structures with high angle curved laminae (arrow); (f) Asymmetrical small-scale HCS-like structures with low angle curved laminae (long arrow) and hummocky strata growth vertically into flat laminae (short arrow); (g) Symmetrical small-scale HCS-like structures with gently hummocky strata upward (arrow); (h) Same as (g), underlaying climbing ripple lamination with some convex-up laminae (long arrow); b： Bi-directional cross-lamination; c： Combined-flow-ripple lamination; g： Normal graded layer; h： Small-scale hummocky cross-stratification-like structures; q： Quasi-planar lamination; w： Wave-ripple lamination, include discordant foresets lens, offshooting lamination and undulatory lamination; (b) and (g) are medium-bedded fine-grained sandstone; (c), (e) and (h) are thin-bedded siltstone; (d) and (f) are thin-bedded medium-grained sandstone and medium-bedded clayish siltstone respectively
